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Date: Mon, 7 Dec 2015 14:49:34 +0100
From: Juergen Borleis <jbe@...gutronix.de>
To: rtc-linux@...glegroups.com
Cc: Alessandro Zummo <a.zummo@...ertech.it>,
Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
linux-kernel@...r.kernel.org, kernel@...gutronix.de
Subject: [PATCH 3/3] RTC/PCF85063: fix time/date setting
When setting a new time/date the RTC's clock must be stopped first, in
order to write the time/date registers in an atomic manner.
So, this change stops the clock first and then writes the time/date
registers and the clock control register (to re-enable the clock) in one
turn.
Signed-off-by: Juergen Borleis <jbe@...gutronix.de>
---
drivers/rtc/rtc-pcf85063.c | 96 +++++++++++++++++++++++++++++++++++-----------
1 file changed, 73 insertions(+), 23 deletions(-)
diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c
index abed934..0150e93 100644
--- a/drivers/rtc/rtc-pcf85063.c
+++ b/drivers/rtc/rtc-pcf85063.c
@@ -19,6 +19,7 @@
#define DRV_VERSION "0.0.1"
#define PCF85063_REG_CTRL1 0x00 /* status */
+#define PCF85063_REG_CTRL1_STOP BIT(5)
#define PCF85063_REG_CTRL2 0x01
#define PCF85063_REG_SC 0x04 /* datetime */
@@ -72,6 +73,47 @@ static int pcf85063_read_time(struct i2c_client *client, u8 *buf, u16 size)
return 0;
}
+static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1)
+{
+ int rc;
+ u8 clk_ctrl[2] = { PCF85063_REG_CTRL1, };
+ struct i2c_msg msgs[] = {
+ {
+ .addr = client->addr,
+ .len = 1,
+ .buf = &clk_ctrl[0],
+ }, {
+ .addr = client->addr,
+ .flags = I2C_M_RD,
+ .len = 1,
+ .buf = &clk_ctrl[1],
+ }, {
+ .addr = client->addr,
+ .len = sizeof(clk_ctrl),
+ .buf = &clk_ctrl[0],
+ },
+ };
+
+ rc = i2c_transfer(client->adapter, &msgs[0], 2);
+ if (rc != 2) {
+ dev_err(&client->dev, "Failing to stop the clock\n");
+ return -EIO;
+ }
+
+ /* stop the clock */
+ clk_ctrl[1] |= PCF85063_REG_CTRL1_STOP;
+
+ rc = i2c_transfer(client->adapter, &msgs[2], 1);
+ if (rc != 1) {
+ dev_err(&client->dev, "Failing to stop the clock\n");
+ return -EIO;
+ }
+
+ *ctrl1 = clk_ctrl[1];
+
+ return 0;
+}
+
/*
* In the routines that deal directly with the pcf85063 hardware, we use
* rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
@@ -110,41 +152,49 @@ static int pcf85063_get_datetime(struct i2c_client *client, struct rtc_time *tm)
static int pcf85063_set_datetime(struct i2c_client *client, struct rtc_time *tm)
{
- int i = 0, err = 0;
- unsigned char buf[11];
+ int rc;
+ u8 regs[9];
- /* Control & status */
- buf[PCF85063_REG_CTRL1] = 0;
- buf[PCF85063_REG_CTRL2] = 5;
+ /*
+ * to accurately set the time, reset the divider chain and keep it in
+ * reset state until all time/date registers are written
+ */
+ rc = pcf85063_stop_clock(client, ®s[8]);
+ if (rc != 0)
+ return rc;
+ /* write start register */
+ regs[0] = PCF85063_REG_SC;
/* hours, minutes and seconds */
- buf[PCF85063_REG_SC] = bin2bcd(tm->tm_sec) & 0x7F;
+ regs[1] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */
- buf[PCF85063_REG_MN] = bin2bcd(tm->tm_min);
- buf[PCF85063_REG_HR] = bin2bcd(tm->tm_hour);
+ regs[2] = bin2bcd(tm->tm_min);
+ regs[3] = bin2bcd(tm->tm_hour);
/* Day of month, 1 - 31 */
- buf[PCF85063_REG_DM] = bin2bcd(tm->tm_mday);
+ regs[4] = bin2bcd(tm->tm_mday);
/* Day, 0 - 6 */
- buf[PCF85063_REG_DW] = tm->tm_wday & 0x07;
+ regs[5] = tm->tm_wday & 0x07;
/* month, 1 - 12 */
- buf[PCF85063_REG_MO] = bin2bcd(tm->tm_mon + 1);
+ regs[6] = bin2bcd(tm->tm_mon + 1);
/* year and century */
- buf[PCF85063_REG_YR] = bin2bcd(tm->tm_year % 100);
-
- /* write register's data */
- for (i = 0; i < sizeof(buf); i++) {
- unsigned char data[2] = { i, buf[i] };
-
- err = i2c_master_send(client, data, sizeof(data));
- if (err != sizeof(data)) {
- dev_err(&client->dev, "%s: err=%d addr=%02x, data=%02x\n",
- __func__, err, data[0], data[1]);
- return -EIO;
- }
+ regs[7] = bin2bcd(tm->tm_year % 100);
+
+ /*
+ * after all time/date registers are written, let the address auto
+ * increment wrap around and write register CTRL1 to re-enable the
+ * clock divider chain again
+ */
+ regs[8] &= ~PCF85063_REG_CTRL1_STOP;
+
+ /* write all registers at once */
+ rc = i2c_master_send(client, regs, sizeof(regs));
+ if (rc != sizeof(regs)) {
+ dev_err(&client->dev, "date/time register write error\n");
+ return -EIO;
}
return 0;
--
2.6.2
--
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